Exploring the Chaotic Dynamics of Cocirculating Disease Strains: Toward Agent-Based Modeling

Entering Summer 2022, COVID-19 with its variants and Omicron subvariants was expected to circulate widely. The waning of immunity among the global population against COVID-19, be it from the vaccines or prior infections or both, continued to occur as the year progressed. Meanwhile, with reopening of borders and resumption of social activities, Influenza (flu) also showed signs of an early restoration of its characteristically seasonal peaks. The combined effects of two distinct co-circulating disease strains such as COVID-19 and flu were of great concern to modelers and public health agencies alike. Notably, it was recognized that raising the number of interacting disease strains would quickly lead to complications in traditional ODE-based compartmental models, whereas the process is relatively straightforward in agent-based models (ABMs). This study was an attempt to develop a basic framework which was then used to implement both types of models. Diagnostic tools borrowed from the chaos theory literature were used to draw comparisons of the model outcomes, leading to an updated framework that is more in tune with the ABM approach.